This invention relates in general to electrical systems, such as are commonly used in electrically powered vehicles and the like. In particular, this invention relates to an improved interlock for providing safe access to an electrical system that is cost effective and relatively simple in structure.
Vehicles that utilize electricity as a source of power, such as electric, fuel cell, and hybrid vehicles, often employ an electrical system. A typical electrical system includes a power source that is connected to a device, such as an electric motor controller. The electrical system may further include various electrical components including, for example, fuses, inductors, capacitors, and the like. It is known that some of these electrical components (e.g., capacitors) are capable of storing electrical energy and, therefore, may need to be discharged in order to be safely handled after being disconnected from the power source. Thus, it is known that the power source should be disconnected from the electrical system, and that the stored electrical energy be discharged from the electrical components before contact with such electrical components should occur.
For increased safety, the electrical system may be provided with an interlock that is configured to affirmatively disconnect the power source from the electrical system when access is attempted. Thus, access to the electrical components is affirmatively prevented unless the power source has been disconnected from the electrical system. In some instances, such interlocks are provided with a time delay feature that continues to prevent access to the electrical components for a predetermined amount of time after the power source has been disconnected from the electrical system. This predetermined time delay allows any electrical energy that is stored in the electrical components to be sufficiently discharged for safe handling.
One known example of such an interlock includes a protective cover that is secured to a device in an electrical system by a plurality of threaded fasteners. Access to at least one of the threaded fasteners is prevented by a shroud that, in turn, is electrically coupled to a control circuit. To gain access to the threaded fastener for removal of the protective cover, the shroud must first be detached. Detachment of the shroud is detected by the control circuit which, in response thereto, initiates the disconnection of the power source from the electrical components in the electrical system. A predetermined amount of time (such as a few seconds, for example) elapses as the threaded fastener and the protective cover are subsequently removed, thereby allowing a sufficient amount of time for the electrical components to discharge.
Although known interlocks function in an acceptable manner, such systems may employ devices that are relatively costly and that can be either difficult to assemble and disassemble or that can be incorrectly re-assembled after servicing. Thus, it would be desirable to provide an improved interlock for providing safe access to an electrical system that is cost effective and relatively simple to assemble and disassemble.